Generally, positron emission tomography (PET) detectors have been set in various large medical devices such as, positron emission tomography-computed tomography (PET-CT) devices, positron emission tomography-magnetic resonance imaging (PET-MM) devices, in which PET technologies are applied. PET detectors are used to receive γ rays generated from a patient's body and to provide information related to the locations where photons are excited by γ rays in the sensors to other components of the large medical devices, so that the other components of the large medical devices may process appropriately based on the location information.
As shown in FIG. 1, currently, a PET detector typically includes a crystal array 102, an avalanche photo diode (APD) array 104 coupled with the crystal array 102, and a light guide 106 which is set between the crystal array 102 and the APD array 104. Among them, the crystal array 102 is formed by multiple crystal elements, which are arranged according to a certain design. The APD array 104 is formed by multiple APDs, which are arranged according to a certain design. Each APD contacts with at least one crystal element.
The γ rays generated in the patient's body are received by a certain crystal element in the crystal array 102. The γ rays excite photons inside the crystal element. The photons transmit among several crystal elements in the crystal array 102, and ultimately enter into the APD array 104 through the light guide 106. And then they are received by the APD array.
When the γ rays excite photons inside the crystal element, optical transmission loss may be caused by the light guide 106. As such, only a portion of the excited photons may enter into the APD array 104, resulting in a lower resolution of the PET detector.